Increasing the angle between caudal screw and the transverse plane may aggravate the risk of femoral head necrosis by deteriorating the fixation stability in patients with femoral neck fracture.

Necrosis of the femoral head is the main complication in femoral neck fracture patients with triangle cannulated screw fixation. Instant postoperative fixation instability is a main reason for the higher risk of femoral head necrosis. Biomechanical studies have shown that cross screw fixation can effectively optimize fixation stability in patients with proximal humerus fractures and pedicle screw fixation, but whether this method can also effectively optimize the fixation stability of femoral neck fractures and reduce the corresponding risk of femoral head necrosis has yet to be identified. In this study, a retrospective review of imaging data in femoral neck fracture patients was performed. The cross angle between the femoral neck and the caudal cannulated screw was reported; if the angle between the screw and the transverse plane increased, it was recorded as positive; otherwise, it was recorded as negative. Angle values and their corresponding absolute values were compared in patients with and without femoral head necrosis. Regression analysis identified potential risk factors for femoral head necrosis. Moreover, the biomechanical effect of the screw-femoral neck angle on fixation stability was also verified by numerical mechanical simulations. Clinical review presented significantly larger positive angle values in patients with femoral head necrosis, which was also proven to be an independent risk factor for this complication. Moreover, fixation stability progressively deteriorated with increasing angle between the caudal screw and the transverse plane. Therefore, increasing the angle between the caudal screw and the transverse plane may aggravate the risk of femoral head necrosis by deteriorating the fixation stability in patients with femoral neck fracture.

[Comparison study of minimally invasive percutaneous bridge internal fixator and traditional external fixator in treatment of unstable pelvic fractures].

OBJECTIVE: To evaluate the effectiveness of unstable pelvic fractures treated with minimally invasive percutaneous bridge internal fixator or traditional external fixator. METHODS: The clinical data of 45 patients with unstable pelvic fractures who met the selection criteria between January 2013 and February 2018 were retrospectively analyzed. According to the different surgical methods, they were divided into two groups. In the observation group (25 cases), minimally invasive percutaneous bridge internal fixators were used, and three-dimensional printing pelvic models were used to simulate the reduction and fixation before operation to develop individual reduction strategies. In the control group (20 cases), external fixators were used. There was no significant difference between the two groups in gender, age, cause of injury, fracture type (according to Tile classification), and time from injury to operation ( P>0.05). The operation time, intraoperative blood loss, fracture healing time, and complications were recorded and compared between the two groups. The reduction quality was evaluated according to the Matta standard, and functional recovery was evaluated according to the Majeed scoring standard. RESULTS: All patients were followed up 12-20 months (mean, 15 months). The operation time of the observation group was significantly longer than that of the control group ( t=2.719, P=0.009); no significant difference in intraoperative blood loss was found between the two groups ( t=0.784, P=0.437). There was no significant difference between the two groups in fracture healing time ( t=0.967, P=0.341). According to the Matta standard, the excellent and good rate of the observation group was 92%, and that of the control group was 70%, showing no significant difference between the two groups ( χ 2 =3.748, P=0.053). At last follow-up, according to the Majeed scoring standard, the excellent and good rate of the observation group was 88%, and that of the control group was 60%, showing significant difference between the two groups ( χ 2 =4.717, P=0.030). The incidences of incision and nailway infection, secondary displacement of fracture, and malunion in the observation group were significantly lower than those in the control group ( P<0.05); the differences in incidences of iatrogenic injury of lateral femoral cutaneous nerve, deep vein thrombosis, and loosening of fixation between the two groups were not significant ( P>0.05). CONCLUSION: Minimally invasive percutaneous bridge internal fixator is a safe and effective method for the treatment of unstable pelvic fractures. It has the advantages of minimal trauma, stable fixation, less interference to patients' daily life, early functional exercise, and quickly recovery after operation.

[HEMOSTASIS EFFECT OF COMPRESSION DRESSING THERAPY AFTER TOTAL HIP ARTHROPLASTY].

OBJECTIVE: To investigate the hemostasis effect of compression dressing therapy after total hip arthroplasty (THA). METHODS: Thirty-four patients undergding unilateral THA between December 2014 and March 2015 were randomly divided into observation group (compression dressing group, n = 17) and control group (ordinary dressing group, n = 17). There was no significant difference in gender, age, height, weight, lesion hips, pathogeny, disease duration, and preoperative hemoglobin between 2 groups (P > 0.05). The total blood loss theoretical value, the postoperative drainage volume, the visible blood loss, the hidden blood loss, the total blood transfusion volume, the number of patients receiving blood transfusion, and the related complications were compared between 2 groups. RESULTS: No significant difference was found in operation time and hospitalization time between 2 groups (t = 0.337, P = 0.738; t = 0.140, P = 0.889). The incisions healed by first intention in all patients. Six cases had incision subcutaneous hematoma in the control group, no incision subcutaneous hematoma occurred in the observation group (χ² = 7.286, P = 0.018). No postoperative complications of wound superficial infection and venous thrombosis occurred in 2 groups. After operation, blood transfusion was given in 1 case of observation group and 7 cases of control group, showing significant difference (χ² = 5.885, P = 0.039), and the total blood transfusion volume was 600 mL and 3 200 mL, respectively. There was no significant difference in preoperative blood volume and intraoperative blood loss between 2 groups (P>0.05), but the total blood loss theoretical value, the postoperative drainage volume, the visible blood loss, and the hidden blood loss in observation group were significantly less than those in control group (P < 0.05). CONCLUSION: The compression dressing should be performed after THA because it can effectively reduce postoperative blood loss and the incidence of wound hematoma.

The Expression of HMGB1 in Bone Marrow MSCs Is Upregulated by Hypoxia with Regulatory Effects on the Apoptosis and Adhesion.

Background and Aims. Hypoxia regulates the survival of mesenchymal stem cells (MSCs) but the mechanism is unclear. In hypoxia, the level of high mobility group box 1 (HMGB1) was increased in many cells which may be involved in the regulation of cell biology. The aim is to determine whether hypoxia affects the expression of HMGB1 in bone marrow MSCs (BM-MSCs) and to investigate the role of HMGB1 in the apoptosis and adhesion. Methods. BM-MSCs were exposed to hypoxia (1% O2) and normoxia (20% O2) and the expression of HMGB1 was measured by RT-PCR and western blotting. The apoptosis and adhesion of BM-MSCs were evaluated after interfered by different concentrations of HMGB1. Results. Expression of HMGB1 in BM-MSCs showed a significant upregulation in hypoxia when compared to those in normoxia. The adhesion of BM-MSCs was increased by HMGB1 in a concentration-dependent manner; the apoptosis effect of HMGB1 depended on its concentrations: HMGB1 at low concentration (50 ng/mL) promoted the apoptosis of BM-MSCs while HMGB1 at high concentration (≥100 ng/mL) reduced this apoptosis. Conclusions. Hypoxia enhanced the expression of HMGB1 in BM-MSCs with influences on apoptosis and adhesion and this could have a significant effect on the regenerative potential of MSC-based strategies.

[CLINGING LESSER TROCHANTER OSTEOTOMY WITH WAGNER CONE IN TREATMENT OF CROWE TYPE IV DEVELOPMENTAL DYSPLASIA OF THE HIP IN ADULT].

OBJECTIVE: To investigate the effectivness of the clinging lesser trochanter osteotomy with the Wagner cone in total hip arthroplasty (THA) for Crowe type IV developmental dysplasia of the hip (DDH) in adult. METHODS: Between November 2009 and September 2012, 7 female patients (9 hips) with Crowe type IV DDH were treated by THA procedures of clinging lesser trochanter osteotomy with Wagner cone, aged 24-62 years (mean, 42 years). All patients experienced severe pain and claudication. The left hip was involved in 2 cases, the right hip in 3 cases, and bilateral hips in 2 cases. The Harris score of involved hip was 50.00?7.04. The both limps were discrepancy with an average length difference of 3.4 cm (range, 3-4 cm). The results of Trendelenburg sign were positive. X-ray films showed high complete dislocation of the involved hips. RESULTS: The incisions healed by first intention. There was no complication such as infection, dislocation, prosthesis loosening, neurovascular injury. The average follow-up was 36.4 months (range, 25-48 months). Pain and claudication were improved and all patients could restore to work. The Harris score was improved to 83.42 +/- 6.47, showing significant difference when compared with preoperative score (t=8.90, P=0.00). The results of Trendelenburg sign were negative. X-ray films showed that all patients got a bony union at osteotomy site of greater trochanter at 3-6 months after operation. And the interface between prosthesis and bone was stable. There was no prosthesis loosening or sinking during the follow-up. CONCLUSION: Clinging lesser trochanter osteotomy with Wagner cone could be an option to shorten the femur in THA for patients with Crowe type IV DDH. It is effective in decreasing the risk of neurovascular injury.